After getting raves on Broadway with Andrew Garfield and Philip Seymour Hoffman in “Death of a Salesman,” Finn Wittrock has moved to a family drama farther up I-95, “The Blue Deep,” co-starring Blythe Danner and directed by Bob Balaban. Written by Lucy Boyle, daughter of “Everybody Loves Raymond” star Peter, the autobiographical play debuted at the Williamstown Theatre Festival Wednesday. Bradley Cooper will star at the fest in “The Elephant Man.”